Numerous solutions disclose various propulsors and pumps for marine vessels. Among these solutions, there is provided a propulsor having a body secured in a fairing for reciprocating motion of a working member mounted on a rod of a drive. Drive is produced in a form of a hydraulic cylinder, and a piston-blade is used as a working member for performing motion in the cylinder, which is secured in a propulsor body by means of struts at clearance between body and cylinder forming a nozzle directed to a side opposite to the fairing, thus creating thrust for motion of the water craft at a forward stroke of the piston-blade due to displacement of water from the cylinder at simultaneous filling space between fairing and piston-blade through nozzle and clearance between cylinder and body with water due to hydrostatic pressure and pressure of the piston-blade. At a reverse stroke of the piston-blade, water is displaced from the cylinder between the fairing and the piston-blade through clearance and nozzle, thus also creating thrust for motion of the water craft.
Another solution provides a liquid piston pump for liquids and gases, which may replace the classic diaphragm pumps and the piston pumps, which are used for small and medium flow rates, the liquid piston pump being used especially for replacing the duplex horizontal pumps for a water supply due to the increase of the self-priming parameter and implicitly for a higher safety during operation. The pump comprises a mechanical diaphragm pump or a piston pump provided with a coaxial distribution assembly in two embodiments: one with peripheral suction and central discharge and another with central suction and peripheral discharge structured on a system that allows the preservation of a liquid piston to the extension of the mechanical piston, the system, in its turn, being composed of two devices: 1) a guiding device for the removal of gases, having a tubular distribution chamber with a cavity structured in a lower part with the role of connection with the mechanical pump and an upper part, which is the guiding device proper, the upper part being located above the level of the working chamber having the upper surface strictly limited to the lower surfaces of two concentric valves, one central conical and the other annular peripheral; and 2) a compensation device for the completion of the liquid piston with the role of air-liquid separator, consisting of a suction chamber and a discharge chamber vertically arranged in the extension of the guiding device, connected with the base of the cavities to the peak of guide cavity by means of valves, both the suction orifice and the discharge orifice being located on the dome of the related chambers.
None of the above mentioned solutions has provided a marine engine or propulsor that does not have any moving metallic parts.